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Title page for ETD etd-11282011-120843

Type of Document

Master's Thesis

Author

Rosson, Teresa Ellen

Author's Email Address

teresa.e.tilyou@vanderbilt.edu

URN

etd-11282011-120843

Title

Fluorescence Enhancement of White-Light Cadmium Selenide Nanocrystals

Degree

Master of Science

Department

Chemistry

Advisory Committee

Advisor Name

Title

Sandra J. Rosenthal

Committee Chair

Charles M. Lukehart

Committee Member

David W. Wright

Committee Member

Keywords

CIE coordinates

band gap

emission

dodecanethiol

thiol

fluorometer

uv-vis

hexadecylamine

absorption

trioctylphosphine oxide

dodecylphosphonic acid

Date of Defense

2011-11-28

Availability

unrestricted

Abstract

Advances are being made in lighting technology, as incandescent and fluorescent light bulbs become less efficient compared to solid-state lighting devices, especially light-emitting diodes (LEDs). Cadmium selenide (CdSe) semiconductor nanocrystals are a promising material to use as a light source because of their unique ability to fluoresce different colors of light over the entire visible spectrum, depending on their size. In 2005, Bowers et al. discovered that if CdSe nanocrystals are synthesized to be ultrasmall (~1.5nm in diameter), they emit broad spectrum white light. These white-light nanocrystals offer an alternative to current “white” LEDs because they emit pure white from a single semiconductor material, and they could possibly be manufactured more efficiently than current commercial light bulbs. The drawback to this goal is that the nanocrystal brightness efficiency is only 8-9% immediately after synthesis. Present research is concerned with brightening these nanocrystals, without compromising their white emission, by incorporating various chemicals onto the surface. Here the nanocrystal fluorescence quantum yield has been found to increase with the addition of certain carboxylic acids, most notably with formic acid. The brightest white light that has been measured with this method is 45% efficient—a significant 500% increase from the original nanocrystals and a major step toward commercial applicability. Ultimately, once the efficiency has been sufficiently increased without compromising the balanced white-light emission, the treated nanocrystals could be incorporated onto an LED, leading to an efficient white-light device that is commercially viable and desirable to the consumer.